Rare metastasis of renal cell carcinoma to the bladder with a new hypothesis and literature review: Case report

Background Metastatic renal cell carcinoma (RCC) to the bladder is extremely rare. A total of 1.6% of the patients were found via autopsy reports. Case presentation: A 44-year-old male patient underwent left nephroureterectomy + ureteral cuff resection because of a left endophytic renal mass and suspected upper tract urothelial carcinoma. Pathology revealed papillary renal cell carcinoma (RCC). In the patient with hematuria, a 16x11 mm mass was detected on the left sidewall of the bladder 2 years after nephrectomy. Papillary RCC was detected after complete transurethral resection of the bladder tumor. When we evaluated the literature, we developed the hypothesis that the periureteral venous plexus pathway is involved in metastasis. Left iliac lymph node metastasis was detected via postoperative positron emission tomography (PET-CT). After 6 months of sunitinib treatment, the metastatic lymphadenopathy was found to regress on PET-CT. Conclusion Solitary resectable intravesical metastatic RCC is a good prognostic factor. Late-onset systemic metastasis may be observed and should be considered during follow-up. If necessary, PET-CT scanning should be performed, and the patient can be treated with sunitinib.